Certification of Standard Reference Material 660c for powder diffraction

• Published in: Powder diffraction Vol. 35; no. 1; pp. 17 - 22
• Main Authors: Black, David R., Mendenhall, Marcus H., Brown, Craig M., Henins, Albert, Filliben, James, Cline, James P.
• Format: Journal Article
• Language: English
• Published: United States Cambridge University Press 01.03.2020
• Subjects: Certification; Confidence; Crystal defects; Crystallites; Crystallography; Data analysis; Data collection; Diffractometers; Laboratories; Lanthanum; Line shape; Neutron diffraction; Parameters; Particle size; Raw materials; Reference materials; Sensors; Standard reference materials; United States > US; X-ray diffraction; Standard Reference Material; diffractometer; lattice parameter; certification
• ISSN: 0885-7156; 1945-7413
• DOI: 10.1017/S0885715620000068

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to evaluate specific aspects of instrument performance of both X-ray and neutron powder diffractometers. This report describes SRM 660c, the fourth generation of this powder diffraction SRM, which is used primarily for calibrating powder diffractometers with respect to line position and line shape for the determination of the instrument profile function (IPF). It is certified with respect to lattice parameter and consists of approximately 6 g of lanthanum hexaboride (LaB 6 ) powder. So that this SRM would be applicable for the neutron diffraction community, the powder was prepared from an isotopically enriched 11 B precursor material. The microstructure of the LaB 6 powder was engineered specifically to yield a crystallite size above that where size broadening is typically observed and to minimize the crystallographic defects that lead to strain broadening. A NIST-built diffractometer, incorporating many advanced design features, was used to certify the lattice parameter of the LaB 6 powder. Both Type A, statistical, and Type B, systematic, uncertainties have been assigned to yield a certified value for the lattice parameter at 22.5 °C of a = 0.415 682 6 ± 0.000 008 nm (95% confidence).